Patients with severe heart failure are known to have an increased incidence of thromboembolic events and frequently have a visible thrombus in the left ventricle. Thromboemboli in heart failure patients are usually attributed to the underlying heart failure, and alternative etiologies for thrombus formation are rarely sought. However, anti-phospholipid antibodies and other inherited or acquired clotting abnormalities may contribute to hypercoagulability in heart failure patients and can lead to a persistent high risk for clotting, even after heart transplantation has corrected the underlying heart failure. We report outcomes with heart transplantation in 3 young patients with anti-phospholipid antibodies and a history of pre-heart transplantation thromboembolic events, and demonstrate the importance of post-heart transplantation anti-coagulation in these patients.